The present invention relates to a lubricating mechanism for a linear guide apparatus. More specifically, the present invention relates to a mechanism capable of externally supplying a lubricant freely to a linear guide apparatus in which a slider is supported inside a guide rail and moved axially relative to the guide rail with the intermediary of balls that rollingly circulate along rolling grooves via ball circulation passages within the slider.
Among the linear guide apparatus of the type to which the present invention is applicable is a miniature linear guide apparatus as illustrated in FIG. 9. The apparatus provides an axially extending guide rail having a U-shaped cross section and a slider 2 which is slidably mounted within the guide rail. Each lateral side of the guide rail 1 has an axially extending loaded ball rolling groove 1B formed in the inner surface that is confronted with another axially extending loaded ball rolling groove 3B which is formed on each lateral side of the body 3 of the slider 2 in the outer surface. The slider 2 also has a ball circulating passage (not shown) on both sides of its interior which extends axially to communicate with the loaded ball rolling groove 3B by curving each end of the slider 2. A plurality of steel balls 6 are installed rollingly within the loaded ball rolling grooves 1B and 3B and the ball circulating passages. When the slider 2 makes a linear movement relative to the guide rail 1 by supporting of the guide rail, the balls roll within the slider to repeat an endless circulation.
The conventional miniature linear guide apparatus is not equipped with a mechanism that enables the external supply of a lubricant into the apparatus after it has been assembled. In order to lubricate the balls 6 while they roll to repeat the endless circulation, one of the following two methods is currently employed:
(1) as shown in FIG. 10, an auxiliary rail 7 is connected to an end of the guide rail 1 and the slider 2 is escaped to the auxiliary rail 7; then, a grease dispenser 8 is used to apply grease G to the loaded ball rolling groove 1B in the inner surface of each lateral side of the guide rail 1; thereafter, the slider 2 is returned to the guide rail 1 and reciprocated along the guide rail, thereby circulating the balls 6 coated with the grease film; and PA1 (2) alternatively, grease is dissolved in a suitable solvent and the linear guide apparatus is immersed in the solution, thereby coating the surfaces of balls 6 with a grease film.
However, these methods have their own disadvantages. In the first method, the reciprocal movement of the slider 2 must be repeated in order to insure that the grease is supplied evenly and adequately to all of the balls 6 within the loaded rolling grooves 1B and 3B, as well as in the ball circulating passages but this operation is not only time-consuming but also inefficient due to the tendency of the grease to splash about.
The second method has the advantage that grease can be readily supplied not only to the balls within the loaded rolling grooves but also to the balls within the ball circulating passages without moving the slider 2. On the other hand, only a small quantity of grease can be supplied in one operation and, hence, it is difficult to insure that the apparatus, once replenished with grease, is kept operated with satisfactory lubrication being maintained for an extended period. Another problem with maintenance is the difficulty of operating a fixedly quantitative application of grease.
Accordingly, even if any conventional methods are adopted, it is practically impossible to take a maintenance action after the lubrication of the linear guide apparatus is deteriorated and the grease refilling operation is even more difficult to perform on a linear guide apparatus equipped with seals.